Air-to-ground communication links using conventional cellular communication devices are becoming increasingly more feasible. As one example, the author of this disclosure has also filed co-pending U.S. patent application Ser. No. 12/827,632 on Jun. 30, 2010, entitled “Aviation Cellular Communications System and Method.” That patent application provides a system for allowing one or more mobile nodes (e.g., mobile phones) to communicate with fixed communication nodes (e.g., cellular base stations) while operating in an aircraft environment. When operating in an aircraft environment, any communication signal transmitted and received by the mobile node would be affected by a Doppler frequency shift given the relatively high speed of an aircraft in relation to the fixed node with which the mobile nodes are in communication.
Doppler frequency shift for many 3G cellular systems (e.g., CDMA2000, W-CDMA, TD-SCDMA, etc.) is a less concerning issue given the top flight speed and path of an aircraft relative to ground towers. However next generation systems LTE will use higher order modulation schemes, yielding 86 to 100 Mbps, that will be more sensitive to Doppler frequency shift, possibly resulting in the loss of communication link or poor bandwidth in high speed/high Doppler frequency shift environments.
Detection and correction of a Doppler frequency shift in the received signal itself (e.g., using a DSP) would be more costly and technically more challenging at very high frequencies and may not be feasible as there is no guarantee that a DSP solution can sample and correct fast enough to avoid bit or symbol loss during synchronization or acquisition. Furthermore, mobile nodes that may be used in an aircraft environment may utilize many different communication standards, including GSM, W-CDMA, CDMA and LTE. As such, it would be preferable to have a Doppler frequency shift compensation method that is applicable on many standards without the need to alter the mobile phone or the cellular base station.